MMS - Ozonesonde Wind and Temperature Comparison

during CR-AVET.P. Bui, J. Dean-Day, C. Chang, R. Castaneda

NASA-Ames Research Center

H. VoemelUniversity of Colorado -- CIRES

Data Sources

• Profiles of WB-57 MMS 1-Hz U, V, T and P during descent to Juan SantaMaria Int Airport

• Vaisala RS-80 radiosonde collected GPS position (latitude/longitude), T and P during Ozonesonde ascents from Heredia, Costa Rica

• Heredia is in close proximity to Juan SantaMaria airport (10km distance separation)

• Sondes launched within 1 hr of WB-57 takeoff or landing on 11 flights (10 descents, 1 ascent)

Data Specifications• Meteorological Measurement System:

Static Pressure (+/- 0.3 mb)Static Temperature (+/- 0.3 K)Wind Velocity (+/- 1.0 m/s)

• Vaisala RS-80 Radiosonde:

Static Pressure (+/- 0.1 – 1.0 mb)Static Temperature (+/- 0.2 K)(Temperature corrected for radiation/ventilation effects)

• Combined Uncertainty at same time/location:Temperature (+/- 0.5 K)

RS-80 Wind Calculation • Deriving Horizontal Winds from Sonde:

GPS position (latitude/longitude/altitude) reported every 1 - 2 seconds during ascent to ~ 30km altitude

Time rates of GPS latitude/longitude define U,V midway between GPS altitude levels

U,V at reported levels estimated from spline interpolation of instantaneous U,V to each GPS altitude level

Resulting U,V profiles were highly variable; Wind profiles subjected to simple vertical averaging to remove scales < 100m (approximately 20 sec during 5 m/s ascent)

Ideal Comparison

• MMS and Sonde BOTH report GPS position:

> Interpolate MMS data to ozone sonde GPS altitude > Minimum temporal/spatial separation

• Ideal conditions for MMS–RS80 comparison:

> All profiles are within 2 hours in time> Spatial separation < 60 km > In generally horizontal homogeneous environment (tropics)

Comparison Summary

MMS warmer than RS-80 by 0.30 +/- 0.20K

MMS Wind Velocity slightly lower (~ 0.65 m/s)

but uncertainty is larger than mean differences

• Pressure Difference is within RS-80 max error (1 mb)

Sonde pressure is lower by 0.7 mb; larger uncertainty at lower altitudes scale with pressure.

19.036.0,1.154.0 msVU